Physical, Optical and FT-IR Studies of Bismuth-Boro-Tellurite Glasses Containing Bao As Modifier
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IOP Conference Series: Materials Science and Engineering PAPER • OPEN ACCESS Physical, Optical and FT-IR studies of Bismuth-Boro-tellurite Glasses containing BaO as modifier To cite this article: B Srinivas et al 2018 IOP Conf. Ser.: Mater. Sci. Eng. 360 012022 View the article online for updates and enhancements. This content was downloaded from IP address 170.106.33.19 on 24/09/2021 at 16:10 Second International Conference on Materials Science and Technology (ICMST 2016) IOP Publishing IOP Conf. Series: Materials Science and Engineering1234567890 360 (2018)‘’“” 012022 doi:10.1088/1757-899X/360/1/012022 Physical, Optical and FT-IR studies of Bismuth-Boro-tellurite Glasses containing BaO as modifier B Srinivas, Abdul Hameed, M N Chary and Md Shareefuddin Department of physics, Osmania University, Hyderabad, TS, India E-mail: [email protected] Abstract. The addition of glass modifier changes the properties of host glass network. The role of Ba2+ as glass modifier has been investigated using physical, UV-Visible and FT-IR studies on xBaO-(30-x)TeO2-35Bi2O3 -35B2O3 ( where x =5,10,15,20 and 25 mole% ) glasses. X-ray diffractograms of crushed glass samples were recorded at room temperature. The absence of sharp peaks in X-ray diffractograms confirms the amorphous nature of the glass samples. Density (ρ) of glass samples were estimated using Archimedes principle. Physical properties such as molar volume (VM), oxygen packing density (OPD), optical basicity etc. were determined. The optical absorption spectra were recorded in the wave length range of 200–1000 nm at room temperature. From the optical absorption spectra indirect allowed optical band gap, Urbach energy, refractive index (n), dielectric constant (ɛ), reflection loss (R), molar refractivity (Rm) and metallization criteria values were evaluated. The refractive index values were decreasing while optical band gap values were increasing with increasing concentration of BaO. IR spectra were recorded in the spectral range 400 - 4000 cm–1. 1. Introduction Borate glasses containing heavy metal oxides (HMO) such as Bismuth oxide, tellurium oxide and Barium oxide have been attracting researchers to synthesis and to study structural and physical properties due to their low melting temperature, widespread glass formation range, high density, high physical and chemical stability, and nonlinear optical properties. Generally heavy metal oxides do not form glasses on their own compare to the conventional glass forming oxides due to their low field strength. In HMO containing glasses, bismuth oxide glasses have shown wide range of applications in the area of glass ceramics, reflecting windows, γ-ray absorbers, thermal and mechanical sensors, optoelectronic devices and scintillation detectors [1, 2]. High polarizable Bi3+ ions and asymmetry of their oxygen coordination polyhedra can assist the non-crystallization of melts [3]. On the other hand covalently bonded B2O3 is a very good glass former with interesting physical and chemical properties. 3+ Basically B2O3 glasses are insulating in nature and the B ion in borate crystals and glasses usually coordinates with either three or four oxygen atoms forming [BO3] or [BO4] structural units. Borate glass is well-known and best choice as optical material for its high transparency, low melting point and high thermal stability [4]. A.M. Abdelghany et.al [5] have prepared and characterized the borate glasses containing SrO substituting both CaO and NaO for their bioactivity or bone bonding ability. They have confirmed the formation of nodular texture of calcium phosphate (hydroxyapatite) and transform to micro-grains with increase of SrO. Tellurite glasses have paid extensive attention as Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1 Second International Conference on Materials Science and Technology (ICMST 2016) IOP Publishing IOP Conf. Series: Materials Science and Engineering1234567890 360 (2018)‘’“” 012022 doi:10.1088/1757-899X/360/1/012022 promising candidates for optical fibers, ultra-fast optical switching devices and high non-linear optical devices because of their low-phonon energy, high refractive index, high polarisability of the non- bonding electron lone pair of Te4+ ions and low crystallization ability [6-8]. However, it must be noted that pure TeO2 does not possesses its own glassy network, under normal melting conditions. Hence addition of network modifiers or glass forming oxides is needed to form tellurite-based glasses [9]. Structural and physical properties of glasses can be altered by the addition of a network modifier such as alkali or alkaline earth oxides and sometimes both alkali and alkaline earth oxide combinations. These network modifier oxides generate non-bridging oxygens (NBO) in the glass network by breaking the bridging oxygen bonding. 2. Experimental Bismuth-Boro-tellurate glasses containing BaO as network modifier were prepared with the composition xBaO-(30-x)TeO2-35Bi2O3-35B2O3 (with the glass codes as, x=5; BTBiB1, x=10;BTBiB2, x=15; BTBiB3; x=20; BTBiB4 and x=25;BTBiB5) by melt quenching technique. Analytic reagent grade chemicals of highest purity BaO, TeO2, Bi2O3 and B2O3 were used as starting materials which are thoroughly mixed in an agate mortar for 20 min. The batch materials were taken in porcelain crucibles and placed in an electrically heated muffle furnace kept around 1200 to1280 K for about one hour, until a bubble free, clear and homogeneous melt was obtained. The homogeneous melt was then quickly poured onto a stainless steel plate and pressed with another stainless steel plate, both were maintained at 500 K. The obtained glass samples were kept at 500K for 5h to relieve the thermal strains in the glass. Density measurements were carried out at room temperature using the Archimedes method with xylene as the immersion liquid. The X-ray diffractograms were recorded at room temperature using the Philips X-ray diffractometer with copper Kα tube target and nickel filter operated at 40 kV, 30 mA. The optical absorption spectra of all the glass samples were recorded at room temperature on a UV–VIS spectrophotometer (model JASCO V 570) in the wavelength range 20 0–1000 nm. The FTIR spectra were recorded at room temperature by using a Perkin Elmer Frontier FTIR in the wave number range (400–4000 cm−1). 3. Results and discussion 3.1 X-ray diffraction XRD patterns of xBaO-(30-x)TeO2-35Bi2O3-35B2O3 glasses are shown in figure 1The absence of characteristic peaks indicated that all the glass samples are amorphous in nature. 3.2. Physical properties The Densities of all of the glass samples were estimated using the formula w air 0.865 (1) wair wxylene where Wair and Wxylene are the weights of the glass sample in air and xylene, respectively, and 0.865 g/cm3 is the density of the xylene at room temperature. The molar volume of the glass composition was calculated using the formula x M V i i (2) m th where xi is the molar fraction, Mi is the molecular weight of the i component of the glass and ρ is the density of the glass. The Molar volume relates directly to the spatial distribution of the oxygen in the glass network. The Density and molar volume values are given in table 1. From the table 1it was found 2 Second International Conference on Materials Science and Technology (ICMST 2016) IOP Publishing IOP Conf. Series: Materials Science and Engineering1234567890 360 (2018)‘’“” 012022 doi:10.1088/1757-899X/360/1/012022 that the density increases from 5.73 to 6.12 g/cm3 with the increase of BaO content. This could be due 3 3 to the higher density of BaO (ρ = 5.72 g/cm ) than that of TeO2 (ρ = 5.67 g/cm ). Figure 2 shows the variation of Density (ρ) and Molar volume (Vm) as a function of BaO content. From the figure 2 it was found that the density and molar volume shows opposite behavior [10, 11]. Oxygen packing densities (OPD) of glass samples were calculated using the expression given below and the values obtained were tabulated in table 1. OPD= O (3) M n Here On is total number of oxygen atoms per chemical formula. From the table 1 it was observed that the OPD values were found to decrease from 59.28 to56.86 mol/l. This decrease in OPD values may be attributed to the increase in molecular weight of the glass. 6.2 45.0 44.8 6.1 44.6 44.4 BTBiB1 6.0 44.2 44.0 BTBiB2 5.9 43.8 BTBiB3 Density(g/cc) 43.6 5.8 Molar Volume (cc) intensity (arb.units) intensity BTBiB4 43.4 BTBiB5 5.7 43.2 Density Molar volume 43.0 10 20 30 40 50 60 70 80 5 10 15 20 25 2 BaO mole % Figure 1. XRD patterns of xBaO-(30-x)TeO2- Figure 2. Variation of density and molar 35B2O3-35Bi2O3 glasses volume with BaO content 3.3. Optical Band Gap and Urbach Energy The optical absorption spectra of the glass samples are shown in figure 3. The power law region is clearly observed in absorption spectra and fundamental absorption edges are not sharp. This is the characteristic feature of amorphous glass samples. From table 1, it was observed that that the fundamental absorption edge shifts to higher wavelength side with an increase of BaO content. Absorption coefficient near the edge of each curve was determined by using the relation 1/ tlogI0 / I (4) where log (Io/I) is the absorbance, I0 and I are the intensities of incident and transmitted light respectively. According to Davis and Mott[12], the absorption co-efficient as a function of photon energy is given by the relation n B(h Eopt) / h (5) where Eopt is the optical band gap energy, B is the constant related to the extension of the Urbach tail and „n‟ take the values of 2, 1/2, 3, and 3/2 depending on the nature of electronic transitions responsible for absorption.